The Vanishing Valentine
Watch a Valentine-themed demo that uses the oxidation and reduction of resazurin to turn a colorless solution pink. The solution returns to colorless as it sits undisturbed.

Valentine’s Day Color Change
Here’s another color change experiment with a pink solution ntaining phenolphthalein, water, and ammonia. Find out how it changes to colorless solution when heated and then returns to pink when cooled due to a shift in equilibrium.